1. Field of the Invention
This invention relates to a portable off shore well installation appartus for the reduction of the pollution caused by petroleum fluids seeping from underwater drilling operations. More particularly, it relates to a pollution control curtain which surrounds the underwater portion of an oil derrick or drilling platform.
2. Description of the Prior Art
Production of oil and gas from off shore locations is now commonplace in many parts of the world using equipment such as drilling platforms, oil derricks and the like. These platforms usually comprise a rectangular truss-like structure known as a jacket. Upon discovery of a field, the jacket is towed to sea, set in position and then anchored.
When the drilling is commenced, one problem that frequently arises is controlling the seepage of petroleum fluids and other contaminants from around the well head. Underwater pollution control apparatus of many designs have been developed for containing such pollutants. Some such apparatus comprise a water impermeable extension sleeve or curtain having submerged anchor means secured to the bottom thereof and a float ring secured to the top of the extension sleeve.
Typically, the contracted sleeve is set in position around the well point and then anchored. Following the installation of the sleeve, the derrick or platform is installed within the area defined by the sleeve in the manner hereinbefore described. The float ring, attached to the top of the sleeve, is then inflated to extend the sleeve toward the surface of the water such that the sleeve will surround the underwater portion of the derrick. The extension sleeve type of pollution control curtains, through which drilling equipment is operated between the surface and the well head, are not designed efficiently to control the pollution problem and are not easy to install and remove from a well site.
Prior to this invention, a float ring was the sole means for extending a pollution control sleeve or curtain through as many as several hundred feet of water. A float ring alone, however, does not provide uniform axial extension of the sleeve, and more particularly, the float ring must be very large and cumbersome in order to extend the sleeve at all.
The typical anchor means used to secure the bottom portion of the sleeve to the sea floor is either a hook-like shaped configuration, a non-buoyant weight, or a combination of the two. When hooks are used to anchor a pollution control curtain the task of imbedding the hooks into the sea floor, upon installation, and dislodging them upon removal of the curtain, is time consuming and hazardous. A curtain comprising a heavy non-buoyant anchor, as an alternative, will quickly sink to the sea floor upon installation. Consequently, the bottom portion of the curtain will be very difficult to direct onto a predesignated site about the well point. The weight of such a heavy anchor also makes removal of the curtain from the well point area toilsome.